Fuel cells have been and are proposed for use as a power source in many applications. A typical fuel cell assembly includes a plurality of individual fuel cells stacked one upon another to form a fuel cell stack which is held in compression. Typically, each fuel cell comprises an anode layer, a cathode layer, and an electrolyte interposed between the anode layer and the cathode layer. The fuel cell stack requires a significant amount of compressive force to squeeze the fuel cells of the stack together. The need for the compressive force comes about from the internal gas pressure of the reactants within the fuel cells plus the need to maintain good electrical contact between the internal components of the fuel cells.
To apply the compressive force, the fuel cell stack is positioned between a pair of rigid endplates that apply a compressive force on the fuel cell stack. Electrically conductive terminal plates are disposed between the endplates and the fuel cell stack and are used to conduct electrical current between the fuel cell stack and the system in which the fuel cell assembly is employed. The fuel cell stack requires gaseous reactants (anode reactant and cathode reactant) to be supplied to and removed from the fuel cell stack to produce electricity. A coolant flow is also provided to and removed from the fuel cell stack to keep the stack at a desired operating temperature. These gaseous reactants and coolant can be humid flows and are supplied to the fuel cell stack by manifold headers. The headers pass through one or both of the endplates and are sealed against the terminal plate. The gaseous reactants and coolant are supplied to the fuel cell stack via the headers. With the header seal being against the terminal plate, the humid fluids (gaseous reactants and/or coolant) are in contact with the terminal plate. Ambient conditions and the voltage (electrical potential), which is applied to the terminal plates, can create electrolysis and cause corrosion of the terminal plate. Corrosion of the terminal plate is undesirable because it could decrease the lifespan of the fuel cell assembly and also contaminate the streams flowing through the headers.
The terminal plates are made from a good conductor, (e.g., aluminum or copper) to facilitate the current flow between the fuel cell stack and the system in which the fuel cell assembly is employed. To protect the terminal plates against corrosion, various coatings have been used on the terminal plate. The coatings, however, can be expensive and cost prohibitive (e.g., made of gold). Additionally, the coatings can have a limited lifespan such that the life of the fuel cell assembly is reduced even with the use of the coatings. Furthermore, the coatings can be sensitive to minor damage, such as scratches, and result in poor performance or allowing the corrosion process to occur. Thus, an inexpensive way to inhibit and/or prevent corrosion of a terminal plate is desirable.